Henry James once remarked that a young woman with literary talent could look through the windows of Chelsea Barracks and write a novel about life in a Guard's regiment. Perhaps. By the same token, a bold writer might look down from the Westway at the clutch of caravans, car wrecks, junk and scrubland nestling alongside Latimer Road and make a stab at a story of Gypsy life. You would have to be wildly reckless, however, to attempt a novel about a singer and poet set among Gypsies in Slovakia after the second world war, and you would have to be as gifted and as skilful as Colum McCann to succeed at it.

Zoli, McCann's eponymous heroine, is "a tall young woman ... not beautiful, or not traditionally so anyway, but the sort of woman who stalled your breath. She held herself at the door nervously, as if she were a bowl of water that would not be allowed to spill." At the age of six she watches her parents, forced by fascist soldiers at night on to a frozen lake, sink and drown as day comes and the ice melts. With her grandfather she joins a new kumpanija or group, teaches herself to read and write and becomes celebrated as a singer, a custodian of Gypsy tradition, a "voice from the dust".

Gypsies are the most harassed, demonised and reviled minority in Europe. Under the Nazis half a million of them were exterminated; under communist regimes their culture was suppressed and they were forced out of their caravans, deprived of social services and even sterilised. They still hold out against assimilation, preserving their own customs and laws, stubbornly oblivious to what we - the gadzos - think of them. "They have no monuments, no anthem, no ruins, and no Book," wrote Isabel Fonseca in Bury Me Standing, her brilliant account of Romany culture (an inspiration for Zoli). "Instead of a sense of a great historical past, they have a collective unease, and an instinctive cleaving to the tribe."

McCann takes this self-contained universe, whose "politics are road and grass", and confronts it with its polar opposite - a hermetic society at whose frozen heart is the urge to re-engineer and homogenise the soul: postwar communism. For a brief period at the end of the war, the new Czechoslovak government seeks to embrace the Gypsies - curing their backward habits and lack of literacy is an exemplary reform project. A celebrated Slovak poet, Martin Stransky, becomes Zoli's champion and is joined by a young English zealot, Stephen Swann, who "foresaw a world raised up in an immense arc and everyone beneath it looking up in admiration". Swann persuades Zoli to allow him to record her songs and write them down. She becomes a poet and, against her instinct and the will of her tribe, she falls in love with him. He persuades her to publish some of her work; she changes her mind but he betrays her by going ahead with publication. For allowing her poems to be published and promoted by the state, she is condemned by her community to "Pollution for Life: The Category of Infamy" and becomes an exile. The traveller becomes a wanderer. "I have sold my voice," she says "to the arguments of power."

As in his previous novel, Dancer, McCann tells his story from several different perspectives - a contemporary journalist, Swann, Stransky, and Zoli herself. With each voice McCann performs an astonishing feat of ventriloquism and mimicry, even creating one of Zoli's poems. In Dancer he impersonated the much documented and highly mythologised Rudolf Nureyev, weaving imagined accounts of fictitious characters into a fabric of documentary truth which portrayed a man who went from near-starvation in wartime Russia to an excess of fame and self-gratification in New York, Paris and London: "I dance so much - too much - in order not to think of home."

The homeless Zoli, driven by guilt and shame, drifts from Slovakia to Austria to Italy and finally, old and at peace with herself, to France. If at times the brutality of her penitential journey seems excessive and prolonged, it's a mark of the success of the writing that one's instinct is to blame her rather than the novelist and to accept the authority of her self-criticism: "Once, as a child, travelling with her grandfather, she had seen a hunger artist in a village west of the mountains. He had made a spectacle of his starvation."

This is typical of the near pitch-perfect control of character and narrative. I don't know whether McCann's account of Gypsy life is true, but I was more than happy to be convinced by the dense cascade of fiercely memorable smells, sounds and visual images. His novel is a hymn to specificity, a clamour against homogenisation and, while the epigrammatic terseness often edges on aphorism - "adoration's more fragile than rope", "certain things will take the life from you" - McCann doesn't fall for ersatz philosophising or elevate his Gypsy characters into noble savages. For all the invocation of honour, their world is harsh and brutish. When Swann is beaten up in Zoli's kumpanija, she observes "They're only keeping warm, Swann, that's all."

The Gypsy ethos acts as a ragged template against which the rest of the world is measured. Zoli finds peace and redemption through an Italian, the dissident black sheep of a wealthy family: "I asked Enrico why he had not asked me anything about being a Gypsy and he asked me why I had never asked him anything about not being one. It was perhaps the most beautiful answer I have ever heard." I don't know if Henry James would have approved of this novel; Zoli certainly would.

Richard Eyre's National Service: Diary of a Decade at the National Theatre is published by Bloomsbury.